1. Field of the Invention
The present invention relates to a shoe sole, capable of horizontally maintaining an inner bottom section of footwear when a user walks. More particularly, the present invention relates to a shoe sole, in which a plurality of protrusions are provided on a bottom surface of an outsole such that the protrusions can move independently from each other, a mid-sole and an insert are sequentially stacked on the outsole, and a plurality of elastic protrusions protrude downward from a bottom surface of the insert by passing through the mid-sole in order to support the protrusions of the outsole, so that the protrusions of the outsole can move independently from each other while being supported by the elastic protrusions even if load is applied to the shoe sole, thereby horizontally maintaining an inner bottom section of the footwear.
2. Description of the Prior Art
Recently, as the standard of living rises, various leisure activities have been increasingly proposed. In this regard, there are great demands for functional footwear suitable for the leisure activities. For this reason, various types of functional footwear suitable for the leisure activities have been developed and appeared on the market. Although structures of the footwear may vary depending on the functional purposes thereof, the footwear basically includes a shoe sole and an upper coupled to an upper portion of the shoe sole.
In addition, the shoe sole includes a mid-sole for providing cushion to the footwear, and an outsole provided at the outermost portion of the shoe sole such that the outsole can make contact with the ground. In the above shoe sole of the footwear, the mid-sole is fabricated using various synthetic resins by foaming the synthetic resins such that an elastic property can be imparted to the mid-sole. In addition, the outsole is made from rubber materials such that the outsole has abrasion-resistant and sliding-resistant characteristics.
In particular, recently, EVA (ethylene-vinyl acetate copolymer) resin having light weight and superior shock-absorbing and restoring properties has been extensively used as a material for the mid-sole. Since the mid-sole must have a property different from that of the outsole, the mid-sole is fabricated separately from the outsole and then is bonded to the outsole by applying an adhesive between the outsole and the mid sole, thereby obtaining the shoe sole of the footwear.
A basic purpose of the shoe sole of the footwear is to protect the sole of a foot while attenuating impact applied to the human body through the foot. In this regard, various shock-absorbing structures have been developed in order to reduce impact applied to the human body through the shoe sole of the footwear. For instance, a shock-absorbing gel has been suggested. However, since only a small amount of shock-absorbing gel is applied to a heel part of the footwear, the shock-absorbing gel cannot sufficiently absorb impact applied to the human body.
In order to solve the above problem, various shock-absorbing structures suitable for the shoe sole have been filed and registered in Korean Intellectual Property Office. For instance, Korean Unexamined Patent Publication No. 2004-54868 discloses a “shoe sole having shock-absorbing function”.
FIG. 1 is an exploded sectional view illustrating the shoe sole disclosed in Korean Unexamined Patent Publication No. 2004-54868. As shown in FIG. 1, the shoe sole includes a mid-sole 10 formed at front and rear portions thereof with installation recesses 11 and 12, respectively. In addition, a plurality of insertion recesses 13 and 14 are formed on bottoms of the installation recesses 11 and 12. A plurality of shock-absorbing sponge members 15 and 16 are fixedly inserted into the insertion recesses 13 and 14 formed in the installation recesses 11 and 12, respectively. In addition, a transparent window 21a is installed at front and rear portions of an outsole 20, on which the mid-sole 10 is stacked, such that a user can view the shock-absorbing sponge members 15 and 16 provided at front and rear portions of the mid-sole 10.
The shoe sole having the above structure can absorb an external pressure applied thereto through the outsole 20, because the shock-absorbing sponge members 15 and 16 are coupled with the mid-sole 10, respectively. However, since only the upper end potions of the shock-absorbing sponge members 15 and 16 are fixedly inserted into the insertion recesses 13 and 14, the shock-absorbing sponge members 15 and 16 may be easily released from the insertion recesses 13 and 14, if the external pressure is continuously applied to the shoe sole. In addition, since the outsole, on which the mid-sole is stacked, is fabricated as one piece, the external pressure applied to the front or rear portion of the shoe sole may be distributed over the whole area of the shoe sole.
In addition, Korean Unexamined Patent Publication No. 1998-76776 discloses a “shoe sole including a cushion tube having a dual cavity”. FIG. 2 is a schematic view illustrating the structure of the shoe sole disclosed in Korean Unexamined Patent Publication No. 1998-76776. As shown in FIG. 2, the shoe sole includes an inner tube 20 interposed between upper and lower covers 20 and 30, in which a plurality of cylindrical cavity sections 11 are formed in the inner tube 20 while being connected to each other on the same plane by means of a plurality of passages 12.
The shoe sole having the above structure can provide sufficient cushion because the inner tube is filled with air and air layers are formed between the inner tube and the upper cover and between the inner tube and the lower cover. However, the shoe sole may provide excessive cushion. In this case, stability of the user wearing the footwear may be degraded. In addition, the structure of the shoe sole is so complicated that the production of such a shoe sole is not economical.